The lifetime of a patent is 20 years, but many patents get abandoned before completing this duration. This may be in part due to the high maintenance fee required by United States Patent and Trademark Office (USPTO), lack of demand for licensing, limited scope for workability in dynamic market situation, deficit of investment in taking it forward, change in the priorities of the inventor or emergence of more affordable or frugal competitive products. We have created a knowledge repository of abandoned patents in USPTO which are available for use by the scholars, entrepreneurs and others in the society. This repository has additional open access features compared to the earlier repository by Pearce such as the names of inventors, the country of inventors, date of abandonment along with the status of the patents, assignee history, number of citations, CPC, NBER and WIPO categories of each patent and entity status.In this paper we have analyzed some trends in the rate of abandonment over the years vis a vis non-abandoned or active patents over the years. We have also explored the number of abandoned and non-abandoned patents in different sectors based on the Cooperative Patent Classification (CPC) of patents. We have created a framework to classify the patents into separate categories based on the filing and abandonment rate. We have taken forward the work on patent lifecycle and used it to understand lifecycle of patent sectors. We have also created a quantitative metric, called as obsolescence rate, to identify the rising and declining sectors. Based on the obsolescence rate, sectors such as Heterocyclic Compounds (CPC category: C07D); Information Storage Based On Relative Movement Between Record Carrier And Transducer (CPC category: G11B); and Apparatus For Physical Training, Gymnastics, Swimming, Climbing, Or Fencing; Ball Games; Training Equipment (CPC category: A63B) and which are to the right of the reference line have a higher obsolescence rate and are hence declining sectors. Similarly, categories such as Computer Systems Based On Specific Computational Models (CPC category: G06 N); Systems For Controlling Or Regulating Non-Electric Variables (CPC category: G05D); and Control Or Regulating Systems In General; Functional Elements Of Such Systems; Monitoring Or Testing Arrangements For Such Systems Or Elements (CPC category: G05B) are on the left of reference line and are hence the rising sectors.